Vol. 54.] FAUNA OF THE SKIDDAW SLATES. 477 



Occurrence. — EUergill Beds = Upper Skiddaw Slates. 



Localities. — Thornship Beck, near Shap ; Ashlock Sike. 



Note. — The foregoing distinction, between ' dichotomous ' and 

 * lateral ' branching, is arbitrary. In the above species, and some 

 of those next to be described, I call the branching lateral when 

 the original stipe continues to grow in the same direction after 

 division as before, but dichotomous when continuation of growth 

 in the original direction would bisect the angle between the two 

 stipes resulting from such division. The appearance of the rhab- 

 dosoma in the two cases is very different. 



I have been unable to determine whether such lateral branching 

 results merely from the unequal instead of equal division of the 

 common canal, which has been shown to occur in true ' dichotomy.' ^ 

 It might conceivably be of a totally different nature, as, for example, 

 the result of budding from one of the thecae of the main stipe ; but 

 certainly in some cases the first view is the correct one. 



Note on the Genera Temnograptus^Wioh.-, ScIiizograptus^Wioh.', 

 Trochograjotus, Holm ; Holograptus, Holm ; and Rouvilli- 

 graptus^ Barrois. — The species belonging to the genera Temno- 

 graptus, Schizograptas^ and TrocIiograp>tiis, which will now 

 be described, are closely allied to each other and to the genera 

 Holograptus and Rouvilligraptus. The appended table (I, 

 p. 478) indicates some of the more important differences 

 between them. 



Genus Temnograptus, Nich. 



Temnograptus multiplex, Nich. (Fig. 6, p. 479.) 



1868. JDicJiograpsus multiplex, Nich. Quart. Journ. Geol. Soc. vol. xxiv, p, 129 & 

 pi. vi, figs. 1-3. 



1876. Temnograjptus multiplex, Nich. Geol Mag, dec. 2, vol. iii. p. 248. 



There is only one specimen of this species in the Woodwardian 

 Museum, and if the branching is dichotomous, as it appears to 

 be, there are at least six orders of stipes. These result from the 

 dichotomous division of one of the stipes of the 2nd order; all 

 the others are incomplete. 



The stipes of the 1st order are short, being about ^ inch in 

 length ; those of the 2ud order are rather longer than ^ inch : the 

 stipes of the remaining orders arise as a result of dichotomous 

 division at intervals of about an inch. 



The angles between the stipes diminish steadily as they get farther 

 away from the base : — 



Angle between two stipes of Order 2 = 90° (about) 

 „ „ of Order 3 = 75° (about) 



of Order 4=70° (about) 

 „ „ of Order 5=50° (about) 



of Order 6=40° (about) 



This may or may not be a character of importance. 

 Occurrence. — Middle Skiddaw Slates. 

 Locality. — Near Peelwyke, Bassenthwaite. 



1 Holm, Geol. Foren. Stockholm Forhaudl. vol. xvii (1895) p. 319. 



